hadoop Hadoop commands Hadoop v1 Commands


Example

1. Print the Hadoop version

hadoop version

2. List the contents of the root directory in HDFS

hadoop fs -ls /

3. Report the amount of space used and

available on currently mounted filesystem

hadoop fs -df hdfs:/

4. Count the number of directories,files and bytes under

the paths that match the specified file pattern

hadoop fs -count hdfs:/

5. Run a DFS filesystem checking utility

hadoop fsck – /

6. Run a cluster balancing utility

hadoop balancer

7. Create a new directory named “hadoop” below the

/user/training directory in HDFS. Since you’re

currently logged in with the “training” user ID,

/user/training is your home directory in HDFS.

hadoop fs -mkdir /user/training/hadoop

8. Add a sample text file from the local directory

named “data” to the new directory you created in HDFS

during the previous step.

hadoop fs -put data/sample.txt /user/training/hadoop

9. List the contents of this new directory in HDFS.

hadoop fs -ls /user/training/hadoop

10. Add the entire local directory called “retail” to the

/user/training directory in HDFS.

hadoop fs -put data/retail /user/training/hadoop

11. Since /user/training is your home directory in HDFS,

any command that does not have an absolute path is

interpreted as relative to that directory. The next

command will therefore list your home directory, and

should show the items you’ve just added there.

hadoop fs -ls

12. See how much space this directory occupies in HDFS.

hadoop fs -du -s -h hadoop/retail

13. Delete a file ‘customers’ from the “retail” directory.

hadoop fs -rm hadoop/retail/customers

14. Ensure this file is no longer in HDFS.

hadoop fs -ls hadoop/retail/customers

15. Delete all files from the “retail” directory using a wildcard.

hadoop fs -rm hadoop/retail/*

16. To empty the trash

hadoop fs -expunge

17. Finally, remove the entire retail directory and all

of its contents in HDFS.

hadoop fs -rm -r hadoop/retail

18. List the hadoop directory again

hadoop fs -ls hadoop

19. Add the purchases.txt file from the local directory

named “/home/training/” to the hadoop directory you created in HDFS

hadoop fs -copyFromLocal /home/training/purchases.txt hadoop/

20. To view the contents of your text file purchases.txt

which is present in your hadoop directory.

hadoop fs -cat hadoop/purchases.txt

21. Add the purchases.txt file from “hadoop” directory which is present in HDFS directory

to the directory “data” which is present in your local directory

hadoop fs -copyToLocal hadoop/purchases.txt /home/training/data

22. cp is used to copy files between directories present in HDFS

hadoop fs -cp /user/training/*.txt /user/training/hadoop

23. ‘-get’ command can be used alternaively to ‘-copyToLocal’ command

hadoop fs -get hadoop/sample.txt /home/training/

24. Display last kilobyte of the file “purchases.txt” to stdout.

hadoop fs -tail hadoop/purchases.txt

25. Default file permissions are 666 in HDFS

Use ‘-chmod’ command to change permissions of a file

hadoop fs -ls hadoop/purchases.txt
sudo -u hdfs hadoop fs -chmod 600 hadoop/purchases.txt

26. Default names of owner and group are training,training

Use ‘-chown’ to change owner name and group name simultaneously

hadoop fs -ls hadoop/purchases.txt
sudo -u hdfs hadoop fs -chown root:root hadoop/purchases.txt

27. Default name of group is training

Use ‘-chgrp’ command to change group name

hadoop fs -ls hadoop/purchases.txt
sudo -u hdfs hadoop fs -chgrp training hadoop/purchases.txt

28. Move a directory from one location to other

hadoop fs -mv hadoop apache_hadoop

29. Default replication factor to a file is 3.

Use ‘-setrep’ command to change replication factor of a file

hadoop fs -setrep -w 2 apache_hadoop/sample.txt

30. Copy a directory from one node in the cluster to another

Use ‘-distcp’ command to copy,

-overwrite option to overwrite in an existing files

-update command to synchronize both directories

hadoop fs -distcp hdfs://namenodeA/apache_hadoop hdfs://namenodeB/hadoop

31. Command to make the name node leave safe mode

hadoop fs -expunge
sudo -u hdfs hdfs dfsadmin -safemode leave

32. List all the hadoop file system shell commands

hadoop fs

33. Get hdfs quota values and the current count of names and bytes in use.

hadoop fs -count -q [-h] [-v] <directory>...<directory>

34. Last but not least, always ask for help!

hadoop fs -help